631 1) 2 sin 2x - 3 (sinx + cos x) + 2 = 0

4 sinx cosx - 3(sinx + cosx) + 2 = 0. Let t = sinx + cosx. t² = 1 + 2sinxcosx. 2sinxcosx = (t² - 1)/2. 2(t² - 1) - 3t + 2 = 0. 2t² - 3t = 0. t(2t - 3) = 0. sinx + cosx = 0 or sinx + cosx = 3/2. tgx = -1 or √2 sin(x + π/4) = 3/2. x = 3π/4 + πn. No solution for the second case.